Heat resisting crystalline thermoplastic resins (having a crystalline melting point of not less than 150° C.) such as polyacetals, polyamides, aromatic polyesters, polyarylene-sulfides, polyketones, polyether ketones, polyamide imides and polyether nitrites are excellent in mechanical properties and moreover moldability, and therefore are used for functional parts for automobiles, industrial machineries, office automation equipments, and electrical and electronic equipments. Meanwhile there is a market demand for higher chemical resistance, sliding properties and the like, and particularly impact resistance is desired to be enhanced because those resins are generally brittle. Also, heat resisting amorphous thermoplastic resins (having a glass transition temperature of hot less than 150° C.) such as polycarbonates, polyphenylene ethers, polyalylates, polysulphones, polyether sulphones, and polyetherimides are widely used for making the best use of transparency, dimensional stability, impact resistance, and the like, but generally there are problems with chemical resistance, solvent resistance and moldability.
Fluorine-containing resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene/hexafluoropropylene copolymer (FEP), polyvinylidene fluoride (PVDF) and ethylene/tetrafluoroethylene copolymer (ETFE) are excellent in thermal resistance, chemical resistance, solvent resistance, weather resistance, sliding properties, pliability, electrical properties and the like, and are widely used for automobiles, industrial machineries, office automation equipments, electrical and electronic equipments, and the like. However, there are many cases where those resins are inferior in mechanical properties and physical thermal resistance as represented by a deflection temperature under load, as compared with heat resisting crystalline thermoplastic resins, and the uses thereof are within the limited range because the dimensional stability is inferior as compared with heat resisting amorphous thermoplastic resins.
Attempts have been actively made to obtain novel materials by combining a fluorine-containing polymer (including resinous and elastomeric form) with the aforementioned heat resisting thermoplastic resins having no fluorine to modify such resins to eliminate disadvantages of the resins, and on the contrary by combining mainly a resinous fluorine-containing polymer with the heat resisting thermoplastic resin having no fluorine to moldify such polymers.
First, as an example for simply melting and blending by the use of a kneading machine, JP-A-202344/1982 discloses that a fluorine-containing elastomer commercially available is added to improve impact resistance, crack resistance and strength against thermal shock without impairing properties of polyarylene sulfides such as thermal resistance, chemical resistance, and the like. Also, JP-A-165647/1989 and JP-A-110156/1990 disclose that a polymer the, that is to say, a liquid crystal polymer (aromatic polyester or the like) forming an anisotropic melt is added to decrease a coefficient of linear expansion without impairing weather resistance and anti-soil property of a fluorine-containing polymer such as a PVDF and further to improve mechanical properties and moldability. As examples of a blend of a liquid crystal polymer and a PTFE, there are JP-B-5693/1992 and JP-A-230756/1988. JP-A-7850/1975 discloses that it is effective to blend the PVDF for improving water absorption and hygroscopicity of polyamides.
Furthermore, JP-A-23448/1985 discloses an example that a property of release from a mold is improved by blending a fluorine-containing polymer with an aromatic polysulphone composition of which shrinkage from mold dimensions has been decreased by blending fibrous reinforcements such as glass fiber and wollastonite and inorganic fillers such as talc and glass beads.
Also, attempts have been widely and generally made to improve sliding properties of various synthetic resins by blending a PTFE powder.
However, since a surface energy of a fluorine-containing polymer is small, there is a problem that such a polymer is generally short of an affinity with other materials. Therefore, when the fluorine-containing polymer and other materials are melted and blended, there occurs a phase separation. Interfacial adhesion thereof is nearly nothing substantially, and an interfacial adhesive failure occurs easily, the fluorine-containing polymer is difficult to be dispersed in other materials during blending, and an aggregation occurs. Thus it is difficult to display an effect of blending that polymer.
In order to eliminate such drawbacks and to enhance an affinity between different polymers, it is often conducted to add so-called compatibilizing agents as the third component. JP-A-218446/1987 discloses a composition prepared by blending a thermoplastic fluorine-containing elastomer to improve impact resistance of polyarylene sulfides without impairing flowability thereof, and that patent publication describes that it is more effective to add a fluoroaliphatic group-containing polymer to improve an affinity of the polymer. Also, JP-A-62853/1988 discloses a method to add, as a compatibilizing agent, a graft polymer comprising a vinyl polymer having epoxy group and a methyl methacrylate polymer or an acrylonitrile/styrene copolymer when blending polyarylene sulfides and thermoplastic resins containing a PVDF.
Also, claim 2 of the mentioned JP-A-165647/1986, JP-A-197551/1986 and JP-A-263144/1986 disclose that it is more effective to add an acrylic polymer, polyvinyl acetate and polyvinyl methyl ketone, respectively than a simple blending, in blending a PVDF and a polymer forming an anisotropic melt.
JP-A-11109/1989 discloses an example of using, as a compatibilizing agent for blending polyamides and PVDF, a block polymer comprising any one of N-vinylpyrrolidone or methyl(meta)acrylate and any one of unsaturated ethylenic monomer, polycondensated monomer or lactam.
Also, JP-A-98650/1986 and JP-A-110550/1986 disclose that when blending a polyphenylene ether and a fluorine-containing polymer like a PVDF, a copolymer comprising polystyrene and an acrylic polymer is used as a compatibilizing agent, taking advantage of an excellent compatibility of polyphenylene ether with polystyrene and PVDF with acrylic polymer.
However, in JP-A-218446/1987, an effect of an improvement in affinity property is insufficient. It may be because a fluoroaliphatic group in an compatibilizing agent is of low polymerization having carbon atoms of not less than 20. All the other publications substantially describes the examples of using compatibilizing agents having no fluorine, which are synthesized, making use of an excellent affinity between a PVDF and a carbonyl group-containing polymer such as acrylic polymer, and the fluorine-containing polymer is limited to the PVDF. In the method to improve an affinity by the use of such a compatibilizing agent, there is a problem that physical properties of the molded articles deteriorate because chemical resistance and thermal resistance of the compatibilizing agents themselves are inferior to that of a main component, i.e. the polymer.
Also, attempts have been made to improve dispersibility of a composition comprising a fluorine-containing polymer and a thermoplastic resin, by a so-called dynamic vulcanization. JP-A-185042/1991 discloses that, when blending a crosslinkable fluorine-containing elastomer and a thermoplastic polymer having a crystalline melting point or glass transition temperature of not less than 150° C., the dispersibility is enhanced and a thermoplastic elastomer can be obtained by vulcanizing the fluorine-containing elastomer during melting and blending. JP-A-172352/1991 also discloses that a fine dispersion of a fluorine-containing rubber is achieved by improving impact resistance of a polyphenylene sulfide by the use of a fluorine-containing elastomer by utilizing the dynamic vulcanization method.
Though those dynamic vulcanization methods are economically advantageous since the vulcanization of the fluorine-containing elastomer is carried out during melting and blending with other materials, there is a problem that impurities resulting from vulcanizing agents and other additives, which are used in the usual vulcanization methods, remain in a composition, and properties such as chemical resistance of a molded article deteriorate.
On the other hand, there are reports on a composition using a fluorine-containing polymer having a reactive functional group. JP-A-105062/1988, JP-A-254155/1988 and JP-A-264672/1988 disclose examples of blending a matrix polymer and, for instance, a fluoropolyether in which a functional group is introduced at the end thereof, a polymer containing a functional group and a polyfluoroalkyl group having carbon atoms of 2 to 20 and a fluorine-containing elastomer having a functional group. However, any of those examples is a manner to form, a network structure by dispersing the polymer having two kinds of functional groups in the matrix polymer and causing an inter-reaction therebetween and to physically bond that network structure to the matrix polymer, but not a manner to directly utilize a chemical affinity and reactivity with the matrix polymer.
Thus a combination of functional groups of not less than two kinds reacting with each other is necessary without fail, and also it is necessary to provide the conditions for forming the network structure by those functional groups. Also, a fluoropolyether is usually obtained as an oily substance and is expensive, and an effect of addition thereof is only limited to an improvement of lubricity of the matrix polymer. Furthermore exemplified is only such a polyfluoroalkyl group-containing polymer of a low molecular weight which is difficult to be prescribed as a polymer.
As mentioned hereinabove, when blending a fluorine-containing polymer and a thermoplastic resin, it is difficult to obtain a blend having stable characteristics because the fluorine-containing polymer is generally short of an affinity, and physical properties of the molded article obtained using that polymer are deteriorated. In order to improve the affinity, various studies have been made in relation to additives, but the present status is such that a composition comprising a fluorine-containing polymer and a thermoplastic resin, which do not deteriorate thermal resistance, chemical resistance and the like of the composition, has not yet been obtained.
The object of the present invention is to provide a composition comprising various heat resisting thermoplastic resins and fluorine-containing polymers having a functional group, which have a good affinity with the resins and are capable of forming uniform dispersing conditions.